According to Kalle Lasn, one of the founders of Adbusters, "there are two kinds of advertising, two kinds of marketing. There is product marketing, and there is advocacy marketing. You can sell products or you can sell ideas. And when you are selling products, then I think you can call that advertising. And when you are selling ideas that try to subvert advertising, we call it “subvertising.” Because usually, when we are selling an idea we are trying to undermine the system."

That's one way of looking at it. Another way is to view all advertisements in public spaces, which we haven't asked for or given our consent to, as open for public critique; to be altered, disfigured, dismantled and subverted by anyone, without the need to ask permission. As street artist Banksy puts it "asking for permission is like asking to keep a rock someone just threw at your head. They have re-arranged the world to put themselves in front of you. They never asked for your permission, don't even start asking for theirs."

In that spirit, here are some of the best, boldest and baddest subvertising campaigns.

1. Brandalism

Let's start with subvertising on an epic scale. In just one night the UK's Brandalism crew swapped over 300 ads in 10 cities for works of art, creating the largest advertising takeover ever. They mostly utilized advertising spaces on bus shelters and have produced this handy guide so you can do the same. Here's some of their sterling work:

2. Beach Body Ready

Sometimes subvertising can be as simple as standing next to an offensive ad and letting the advertisers know exactly what you think about it. This is what happened when the idiots at Protein World decided to run a series of misogynistic ads. It wasn't long before people started posting pictures of the offending ads and taking matters into their own hands...

3. Manchester Climate Action

As part of a weekend of action against fuel poverty, a group of activists requisitioned a billboard for a sweary stab at the Big 6 energy companies, who had been raking in huge profits while thousands of people died as a result of fuel poverty.

Before you click play in the quiet library/stuffy office, be aware there's loud sweary music in this excellent video 

4. UKIP and Tories

In the run-up to the 2015 UK general election there were a dozen political parties in the running, but only two regularly had their billboards enhanced. I wonder why...

5. Strike! The Special Patrol Group

Saving my personal favourite till last. Strike! Magazine has recently launched an all-out assault on London's bland advertising spaces with urgent calls to wake up, smell the bullshit and take action! From their brilliant Bullshit Jobs ads on the underground, to ads about institutional racism in the police force outside Scotland Yard. Strike! I fucking love you.